public class Test1 {


    //1.判断字符串是否包含子字符串
    public static void main1(String[] args) {

        String str="qwert";
        System.out.println(str.contains("ert"));
    }


    //2.字符串拼接
    public static void main(String[] args) {

        StringBuilder str=new StringBuilder("poijl");
        System.out.println(str);
        str.append("nnnn");
        System.out.println(str);
        System.out.println("==================================");


        StringBuffer str2=new StringBuffer("qweee");
        System.out.println(str2);
        str2.append("nnnn");
        System.out.println(str2);
    }

}
